Understanding Java's Virtual Threads: Lightweight Concurrency in Action
Java 21 introduced virtual threads as a stable feature (JEP 444), fundamentally changing how we approach concurrency on the JVM. In this post, we'll explore what virtual threads are, why they matter, and how to use them effectively.
The Problem with Platform Threads
Traditional Java threads—now called platform threads—are thin wrappers around operating system threads. Each one consumes roughly 1MB of stack memory and involves the OS scheduler for context switching. This makes them expensive:
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